In response to the increase in biological and chemical oxygen demand (BOD/COD) and total organic carbon caused by the formation of algal communities and increase in organic matter in the Nakdonggang River, which are a result of the continuing heat wave and lack of rainfall, the Maegok and Munsan purification plants are operating cutting-edge treatment facilities to monitor water quality on a 24-hour basis. Both purification plants are producing and supplying tap water that meets drinking water standards and is therefore safe to drink.

○ Since January 2018, the biological oxygen demand (BOD) of the Nakdonggang River’s untreated water has maintained an average of 1.8ppm, which corresponds to a 1b grade (good) under the Living Environment Standards for Stream Water outlined in the Framework Act on Environmental Policy (calculated as annual average). With high levels of dissolved oxygen and virtually no contaminants, the tap water of Daegu is clean enough to be used as drinking water (after general purification).

○ The Maegok and Munsan purification plants’ cutting-edge treatment facilities (pre-/post-ozone injection facility, which is an enhanced version of the general purification processing facility, as well as activated carbon adsorption tank, etc.) enable the complete breakdown of organic matter, which can increase in response to the rapid growth of algal communities, as well as the complete removal of toxic substances (e.g., microcystin) and substances that affect the taste and odor of the water (geosmin, 2-MIB).

○ Water quality is evaluated in terms of BOD for streams and COD (chemical oxygen demand) for dams and lakes. The concentration of algae in the Nakdonggang River has decreased significantly. - Blue-green algae cell count for Gangjeonggoryeong Reservoir (as announced by Daegu Regional Environmental Office): 18,741 cells/mL (August 9) → 5,150 cells/mL (August 13)

○ Director Kim Mun-su of Daegu City Hall’s Water Management Division said, “Our advanced treatment facilities are currently being operated in a way that ensures we are able to respond effectively to changes in the water environment, as shown by our 24-hour monitoring of water quality. Daegu citizens do not need to worry about whether their tap water is safe to drink, because we are taking every possible measure to supply safe tap water throughout the city.”